Why does the mesophyll cells contain chloroplasts

The process used by plants and animals to get energy from sugar molecules. Respiration changes oxygen and sugar chemically into carbon dioxide and water and heat. A loosely packed layer of irregularly-shaped cells. Air spaces that surround this cell layer allow gas exchange to take place. Small pores holes located on leaves.

They are usually present on the underside of leaves but can also be found on the upper side as well. A membrane bound structure within the chloroplast. Thylakoids consist of a thylakoid membrane surrounding a thylakoid space or lumen. Thylakoids contain chlorophyll and are where photosynthesis takes place. The process of water movement through plants and eventual evaporation from small pores, or stomata, in leaves.

Strands of vascular tissues connecting all of plant parts in order to transport nutrients and water through phloem and xylem. Investigation Resources About Videos. Your browser is out-of-date. Please update your browser to view this site properly. Update Browser. Resource Library Search Reset. Tiled view List view.

You must be logged-in to favourite. Add to favourites Comment New List Add Favourite and Save to List. Above Image: Diagram showing the special types of cells present in leaves Without leaves, there would not be life on Earth. Leaf Structure Leaves are complex organs consisting of many different cell types see Figure 1 including the epidermis, palisade mesophyll layer, spongy mesophyll layer, and vascular bundles. Leaves have an upper epidermis that is located on the upper part of the leaf.

A cuticle can also sometimes be present on the outside of the epidermis. This waxy layer helps prevent water loss, especially in dry regions. The palisade mesophyll layer is made up of closely-packed, elongated cells located just below the upper epidermis.

They contain chloroplasts and carry out most of the photosynthesis. Vascular bundles are made up of xylem and phloem cells. These are the cells that carry water and nutrients throughout the plant and are visible as the veins in leaves.

The spongy mesophyll layer is located directly below the palisade mesophyll layer. It consists of irregularly-shaped cells that are loosely packed with air spaces in between. Cells in the spongy layer usually contain few chloroplasts especially in dicot plants and are the storage place for the products of photosynthesis.

The air spaces are all interconnected and lead to the outside of the leaf through stomata. The lower epidermis is located on the underside of leaves. Stomata are usually present on the lower epidermis. In order to minimize transpiration that occurs with gas exchange, most dicot plants have their stomata on the lower epidermis. On the other hand, monocot plants such as corn can have their stomata on both the top and bottom sides of leaves. This is because corn leaves grow upright rather than parallel to the ground and therefore both upper and lower surfaces of leaves experience transpiration.

Chloroplasts and Photosynthesis Inside chloroplasts, there are membrane bound structures called thylakoids that are surrounded by the stroma see Figure 2. Stomata and Gas Exchange Stomata or pores in the leaf surface are surrounded by specialized leaf cells called guard cells see Figure 3. How is the opening and closing of stomata regulated?

Glossary Air spaces: Spaces between spongy mesophyll cells where gas exchange takes place. Carbon dioxide: A gas used by plants for photosynthesis; a gas produced as waste by animals during cellular respiration. Chlorophyll: A class of pigments produced in plants that give plants their green colour. Chloroplast: An organelle found in plants and some algae where photosynthesis takes place. Cuticle: A waxy layer usually present on the outside of the epidermis in plants.

Dicot: A group of flowering plants. The seeds in this group of plants contain two seed leaves. Epidermis: A single layer of cells that covers all parts of a plant. Grana singular granum : A stack of thylakoid discs that resembles a stack of coins or pancakes. Guard cells: Specialized cells surrounding stomata that also control stomatal opening and closing. Lamellae: Connect grana stacks together. Monocot: A group of flowering plants.

The seeds in this group of plants contain one seed leaf. Osmosis: The movement of molecules through a semi-permeable membrane from a region of higher concentration to lower in order to equalize the concentration on both sides of the membrane. Oxygen: A gas used by animals during respiration; a gas produced by plants during photosynthesis. Within chloroplasts is chlorophyll , a green pigment responsible for trapping light energy in order to convert carbon dioxide and water into glucose chemical energy and oxygen.

The plant uses the glucose it produces for:. Leaves are adapted for:. Photosynthesis and plants Photosynthesis is an endothermic process that takes part in the chloroplasts found in leaf cells. Storage — the glucose is converted into starch and oils. Useful substances — the glucose is converted into cellulose for cell walls, protein for growth and chlorophyll. Leaf structure Leaves are adapted for: Light absorption.

Gas exchange. Adaptations to maximise light absorption: Each leaf is not in the shade of another. Transparent waxy cuticle — a protective layer that allows light to enter the leaf. It is waterproof in order to prevent water loss by evaporation.